Arrangement in a beating machine for treatment of paper stock



Jan. 10, 1967 A. SKARDAL ARRANGEMENT IN A BEATING MACHINE FdR TREATMENT OF PAPER STOCK 2 SheetsSheet 2 Filed Feb. 17, 1964 FIG.5

FIG.6

INVENTOR. AA'PA ARV/0 JKA/PPAA United States Patent 3,297,262 ARRANGEMENT IN A BEATING MACHINE FOR TREATMENT OF PAPER STOCK Karl Arvid Skardal, Stockholm, Sweden, assignor to Aktiebolaget Celleco, Stockholm, Sweden, a corporation of Sweden Filed Feb. 17, 1964, Ser. No. 345,288 Claims priority, application Sweden, Mar. 21, 1963, 3,068/ 63 1 Claim. (Cl. 241-90) The present invention relates to beating machines for working or treating paper stock of the type in which the beating action occurs within a beating zone, which has the shape of a truncated cone, between the wings of a rotating conical wing wheel and stationary beating means surrounding said wing wheel and comprising a cage of stationary knives, which are distributed in spaced relation around the wing wheel, whereby, during the beating operation, the paper stock will be forced radially out-wards through the interspaces between said knives.

It is an object of the invention to obtain the highest possible beating eifect from a machine of the type referred to.

It is another object of the invention to reduce the mechanical stress on the beating elements, particularly the knives.

It is still another object of the invention to eliminate objectionable noise from the machine during operation.

The invention is chiefly characterized by the fact that the stationary knives are disposed longitudinally of said heating zone and are curved as viewed transversely to said beating zone. In other words, as seen against the beating zone, said knives are curved to a shape resembling that of the curved shape of the teeth of a helical conical gear wheel.

The invention will now be described more in detail with reference to the annexed drawing in which FIG. 1 illustrates a longitudinal section of a known machine of the type to which the invention relates,

FIG. 2 illustrates a detail of the machine according to FIG. 1 taken along the line IIII in that figure,

FIG. 3 illustrates in larger scale a further detail of the same machine,

FIG. 4 illustrates in half the scale of FIG. 3, and

FIG. 5 illustrates in the same scale as FIG. 3 a modification according to the invention of the details according to FIG. 3,

FIG. 6 is a view in side elevation of the rotor of the machine in accordance with the invention, and

FIG. 7 is a fragmentary View in transverse section through the rotor of the machine, the section being taken along line VlI-VII of FIG. 6 looking in the direction of the arrows.

All figures are schematic and only intended to serve as examples without purposes of limitation. Identical details in the several figures are indicated by the same reference numerals. As above noted, and as indicated on the first sheet of the drawing, FIGS. 1, 2, and 3 illustrate a known or prior art machine to which the present invention may be applied.

In FIG. 1 a housing 1 contains a wing wheel 2 with wings 3 and a driving shaft 4 rotatably journaled and surrounded by a rim of stationary knives 5. Knives 5 are su ported at their ends only by means of rings 14 and 15' connected to the opposite ends of the knives and seated in recesses in inwardly extending annular flanges on the housing 1. The beating zone, i.e. the zone within which the outer edges of the Wings 3, as the wing wheel rotates, pass the inner edges of the stationary knives 5, has the shape of a truncated cone of the length L, which at its small end has a diameter d and at its large end has a diameter D. The stationary knives have a thickness S,

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a pitch T and interspa-ces V therebetween (FIG. 2). In addition the housing is divided by partition walls 6 and 7 into a central chamber 8, which surrounds the rim of the stationary knives 5, a side chamber 9, which communicates with the interspaces between the wings 3 of the wing wheel at its small end, and a side chamber 10, which communicates with the same interspaces at the large end of the wing wheel. The central chamber 8 and the side chamber 9 communicate with each other by passages 11 in the partition wall 6.

The machine, fully charged with paper stock, operates in the following way. As the wing wheel rotates it will cause the whole bulk of paper stock, except the part thereof contained in chamber 10, to circulate from the wing wheel radially outwards through the rim of stationary knives via chamber 8, passages 11 and chamber 9 back to the wing wheel. Thereby all parts of the circulating stock will repeatedly pass across the beating zone, thus being repeatedly subjected to beating action. New stock may at the same time be supplied to the circulating stock through nozzle 13 and chamber 10, whereby a corresponding amount of stock is withdrawn from chamber 9 through nozzle 12, or the stock may be passed in the opposite direction from nozzle 12 to nozzle 13.

By trials with machines of fundamentally the illustrated and described type the inventor has found that specific factors are important for the heating efficiency. Thus, it is important that the rim of stationary knives makes resistance to the circulation so that the stock cannot pass through without thereby forming a layer of fibers against the knives 5 within the beating zone, against which layer the wings of the wing wheel can exert an efiicient beating action. The chief factors of influence to that eifect are, on one hand, the absolute width V of the inter Space or slit between adjacent stationary knives, viewed in the direction of rotation, and on the other hand, the relation between that width and the pitch, that is to say V/T, which is a measure of how large a part of the total beating zone faces the through-passages. According to trials V should not exceed 8 mm. and V/T should not be less than 30%, which means that in principle the beating zone should face a larger number of slits between relatively thin knives.

FIG. 3 illustrates a practical application of this principle and shows two adjacent axially directed straight knives 5 as viewed against a beating zone with L==20O mm. and D/d=2. At the d-end a pitch Td=6 mm. is selected, which at the D-end gives the double pitch TD=12 mm. In addition, at the d-end a slit width Vd=2 mm. is selected so as to obtain Vd/Td exceeding 30% to 33%. This gives S=4 mm., which at the D-end, where TD is 12 mm. results in a slit width VD=-8 mm., that is to say, the maximum allowable width, which gives VD/TD:67%. Thus it should be appreciated that an application of the principle now mentioned may result in so slender knives that if secured at their both ends only, they would obtain insufiicient strength against lateral forces exerted against them during the beating operation every time a wing 3 passes in the direction of arrow Z over the slit V. However, any considerable increase of the thickness S of the knives within the scope of the principles mentioned is not possible. Such increase at constant pitch Ta and TDV res ectively will result in a decrease of Vd so that Vd/Td becomes less than 30%. Obviously an increase of Td at constant Vd gives the same result and in addition VD will exceed 8 mm., which then may be counteracted by decreasing L. that is to say by shortening the beating zone axially. Without giving the knives the thickness required due to mechanical resistance without consideration to the principles mentioned and thereby submitting to a lower beating efiiciency, there remain only two obvious steps to take. One is to decrease L, which means that the possible size of the apparatus is decreased, and the other is somehow to provide the knives with additional support between the partition Walls 6 and 7, which cannot be done without a relatively expensive constructive complication and obstruction of the circulation of the stock within the apparatus.

According to the invention, as shown in FIGS. 4-7, inclusive, the knives 5a, at unchanged pitch Td and TD, from their fastening at d along their entire length are instead curved axially, as illustrated in FIG. 4 by the center lines 5b of the knives, that is to say in a manner similar to that of the teeth of a helical conical gear wheel. This leads to the following advantages.

Because of its arched or curved shape in lateral direction, each knife gets considerably higher capacity than the straight knives to resist the lateral forces related above, especially when they occur against the concave side of the knife as a result of a periferal motion of the wing wheel in relation to the knives directed against this side as shown by the arrow Z.

Because of the oblique position of the knives in relation to the wings of the wing wheel the lateral forces from said wings will not suddenly hit the whole length of the knives but will be transmitted gradually along the knives from one end thereof to the other. This eliminates vibratory stresses in the knives, which also leads to an elimination of the very objectionable noise, usually caused by such an apparatus with straight knives.

Because the slit width by straight knives, in the example with reference to FIG. 3, increases (from d to D) to the maximum width 8 mm. at a specific length of the beating zone, this length cannot be increased without this maximum width being passed. With curved knives, however t is possible, by selection of curvature, to moderate the progression of alteration of the slit width. FIG. 5 shows in the same scale as FIG. 3 the D-end of the knives, curved according to FIG. 4, illustrating that in this case the slit width VD, which, as measured on the drawing is about 5 mm., that is to say considerably less than the maximum width, no longer limits the length that the beating zone may be given.

What I claim is:

In a beating machine for treating paper stock, in which the beating operation is efiected within a beating zone, which has the shape of the side wall surface of a truncated cone, between the wings of a rotating conical wing wheel and stationary beating means surrounding said wing wheel, said stationary beating means comprising elongated stationary knives which, supported at their both ends only, run side by side from the small end to the large end of the conical beating zone distributed in spaced relation around the wing wheel so as to form a cage surrounding the wing wheel, in which cage the interspaces between the knives form passages for paper stock from the beating zone radially outwards through said cage, the arrangement that said stationary knives between their end supports extending in a direction substantially axial in relation to the wing wheel from the small end of the beating zone are curved to run along helical paths towards the large end of the beating zone so as, viewed in the direction of rotation of the wing wheel, to restrict the width of said passages through said cage all along the beating zone to not less than percent of the pitch between the knives and within a maximum Width of 8 mm.

References Cited by the Examiner UNITED STATES PATENTS 1,047,356 12/1912 Williams 241l88 X 1,133,181 3/1915 Philipp 241-90 X 2,807,989 10/1957 Schaan 241 FOREIGN PATENTS 398,121 9/1933 Great Britain.

LESTER M. SWINGLE, Primary Examiner. ROBERT c. RIORDON, Examiner.

D. KELLY, Assistant Examiner. 

